The present invention relates to a torque transmission control device for connection at one end to a power source such as an impact wrench that generates an impact load in a rotational direction and at its other end to a bolt head, via an output shaft. The present invention relates more particularly to a torque transmission control device that limits transmitted torque to a predetermined value using a friction clutch mechanism.
A known torque transmission control device with a friction clutch comprises a hollow cylindrical housing with an opening at one end, an output shaft inserted in the housing along the axis of the housing, at least one ring spring provided at the bottom of the housing, at least one ring member engaged with the housing but not with the output shaft, at least one ring member engaged with the output shaft but not with the housing, dry friction rings interposed between the ring members, at least another ring spring provided adjacent the opening with a friction adjustment screw, on top thereof, screwed in the opening by means of a thread from the opening toward the bottom of the housing. The output shaft penetrates the ring springs, the ring members, and the dry friction rings through their central holes. The friction adjustment screw adjusts the friction produced between the ring members, thereby limiting a torque transmitted from a motor connected with the housing to the output shaft to a predetermined value.
A general purpose motor, if connected to the housing, does not inadvertently change a predetermined maximum torque setting because it does not generate an impact load. However, if an impact wrench is connected to the housing, a rotational impact load is transmitted to the friction adjustment screw as a rotational vibration to change the setting of the friction adjustment screw. This causes the predetermined maximum transmitted torque to change during bolt tightening.
An object of the present invention is to overcome the above identified problem to provide a torque transmission control device that prevents rotational vibration from changing the setting of the friction adjustment screw so that a predetermined maximum transmitted torque does not change during bolt tightening operations.